<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .container div {
      height: 200px;
    }

    .left {
      width: 200px;
      height: 100px !important;
      float: left;
      background-color: blue;
    }

    .right {
      background-color: red;
      overflow: hidden;
    }
  </style>
</head>

<body>
  <div class="container">
    <div class="left"></div>
    <div class="right"></div>
  </div>
</body>

</html>